Wireless battery chargers typically operate with a fixed gap of a known distance between a transmission coil and a receiving coil. By knowing the fixed gap, the resonant frequency can be set to give the maximum power transfer with the best efficiency. Typically, the circuit is fixed in structure with the power supplying the circuit also fixed in frequency.
Aircraft wheels may be equipped with inductively coupled coils to communicate between rotating and static frames on and about the wheels. The air gap between various coils is often unpredictable. Manufacturing tolerances of multiple parts coupled together can result in different air gap distances between otherwise similar configurations. Furthermore, the air gap between coils may vary over time with wear and use of the surrounding components. For example, as temperatures change or components settle into varying positions relative to one another, the alignment and spacing between adjacent coils may vary. A fixed circuit with fixed transmission characteristics may not adequately adapt to the varying gap.